Hottse



(No Model.)

H. H. WESTINGHOUSE.

STEAM ENGINE.

Patented Apr. 13, 1886.

INVENTOR, 151. 11mm/ BY fo/afm /1/- im@ ATTORNE WITN ESSES:

#Md/y@ i lhviTnn STATES `'ATENT 'i Trios,

H. HERMAN VESTINGHOUSE, OF PITTSBURG, PENNSYLVANIA, ASSIGNOR TO THE VESTINGHOUSE MACHINE COMPANY, OF SAME PLAGE.

STEAM-ENGINE.

PECFICATIN forming part of Letters Patent No. 340,021, dated April 13,1886.

Application tiled January 13, 1886. Serial No. 188,4'26. (No model.)

To @ZZ whom it' may concern;

Be it known that l, H. HERMAN XVEsTI-NG- HOUSE, residing at Pittsburg, in the county of Allegheny and State ol' Pennsylvania, a citizen`of the United States, have invented or discovered a certain new and useful Improvement in Steam-Engines, of which improvement the following is a specification.

In the accompanying drawings, which make part of this specification, Figure lis a horizontal central section through the cylinder and steam-chest, and aplan view of other members of a steam-engine embodying my invention; and Fig. 2, a vertical longitudinal l5 central section through the steam-chest, with the governor and valve-connections in elevation.

rEhe object of my invention is to provide a steam-engine in which the operative economy zo due to the utilization of steam expansively by compounding may be attained in a high degree, in conjunction with the advantages of structural simplicity and inexpensiveness; to which end my invention, generally stated, consists in the combination, in a compound engine, of a cylinder or cylinders having pistouspaces ot' ditferential areas, a single main or steam distribution valve adapted to supply boiler-steam to the smaller piston-space, to exhaust steam therefrom into the larger piston-space, and, finally, to exhaust it from the larger piston-space, and an automatic cut-off mechanism actuating said distribution-valve.

The improvement claimed is hereinafter more fully set forth.

Automatic cut-oft' engines in which the admission and exhaust of steam to and from the piston is effected by a single distributionvalve, and the speed regulated by a governor 40 which varies the point of cut-off in correspondence with variations in load or pressure, or both, by changing the position ofthe eccentric which actuates thc distribution-valve, are well known in the art of steam-engineering.

The employment ot' mechanism of suoli character is general and approved, and in point of simplicity of construction, as Well as in attaining substantially pertect regulation, it has been generally regarded as satisfactorily answering the requirements of useful and 5J practical service. So far, however, as economy of steam is concerned, it is considered by many to be defective to an extent such as to render its application undesirable in comparatively large engines, or in cases where the attainment of the best results derivable from a high grade of expansion is a leading or materialobject. The ground of such belief is,

in brief, the fact that the valve cannotbe made to perform its functions in a practically per- 6o feet manner for an earlier cut-ott' than about one half-stroke, as in such case there ensues an undue contraction of the area of steam admission, a prei'nature opening of the exhaust, and an increased compression by reason of early exhaust closure, which so far reduces the power of the engine as to counterbalance the gain due to the higher grade of expansion. A further objection is the necessity of excessive clearance to admit of the 7o compression commenced at early points in the stroke.

My invention is designed to enable the simplicity and effectiveness of automatic cut-oli' mechanism to be made available without the sacrifice of the economic advantages of the higher grades of expansion involved by its practical defects, as above indicated, when operated at early points of cut-off, and this object I attain by a novel combination of mem- 8o bers, as hereinafter described, in which, while the limit of effective performance of its functions by the valve is not exceeded, as high a degree of expansion may be attained as is desirable or practicable. 8 5

As an exemplitication of the practice of my invention, the drawings illustrate a singlecylinder double-acting compound engine of the trunk-piston class, having piston-spaces of ditferent volumes, respectively, on opposite 9o sides of its piston; but it will be obvious to those skilled in the art that my improvement is, without change of principle or essential operative members, equally applicable to compound engines of the ordinary type, in which the differential piston-spaces to be filled with boiler-steam and exhaust-steam, respectively, are located in two cylinders of unequal volumes. The cylinder' 1, which is closed at its ends by removable heads 2 3, is fixed upon .a bed-plate, 4, which carries the bearings 5 of a crank-shaft. 6, having a pair otl cranks, 7, connected by a crank-pin in the usual inanner. The piston 8. which tits truly in the cylinder. is formed integral with or secured to a cylindrical trunk, 9, which projects centrally from one side ot' the piston, and passes freely through the cylinder-head 3 nearest. the crank-shaft 6, leakage of steam being prevented by improperly-packed stuffing-box, 10, having a gland or packer, 11. A cross-head. 12, which is fitted to work between guides' 13 on the bedplate, is fixed upon the outer end ol' thetrunk 9. and a pin, 14, passing through the central portion ot' the cross-head, is coupled by a connecting-rod, 15. to the pin ofthe cranks 7. lt will be seen that the presence ofthe trunk 9 reduces the effective area ot' the adjacent side ofthe piston to the annular surface comprehended between its periphery and that ofthe piston, while the entire surface of the opposite side ot the piston heilig subject to steam-pressure constitutes effective area.

vThe maximum volume of the annular space 16 on the trunk side ofthe piston is correspondingly lessL than the maximum volume of the cylindrical space 17 on the opposite side, the ratio ot' difference between said areas and volumes resultant upon therelative diameters ofthetrunk and cylinder, as the same may be apportioned, determining the grade ot eX- pansion practicable in the cylinder,,similarly to the difference of diameters of the cylinders in an ordinary two-cylinder compound engine. Steam is admitted to and exhausted from the cylinder-spaces 16 17 on opposite'sides of the piston by a main or steam-distribution valve, 18, of the piston class, having pistons 19 20 at or near its ends, connected'by an intermediate hollow or tubular body, said valve being xed upon a stem, 21, and fitting truly in a cylindrical steam-chest, 22, cast upon'or secured to the cylinder 1. A port or passage, 23, leadsfrom the outer end of the cylinder-space 16 to the steam-chest, and asimilar port, 24, leads from the outer end of the cylinder-space 17 to the steam-chest. Communication is established, in the traverse of the valve 18, between the ports 23 and 24, through the interior of the body of the valve, by a series of ports, 25 26, located in the end pistons, 20 and 19, respectively. Steam from the boiler is admitted to the steam-chest through a steainsupply opening or nozzle, 27, located therein between the ports 23 and 24, and, after performing its work in the cylinder, is exhausted from the chest through an exhaust opening or nozzle, 28, in the end thereof adjacent to the portv24. The distribution-valve 18 is actuated by an automatic cut-off mechanism, as presently to be described, and in its reciprocating movements within the chest 22 performs the functions of rst admitting boiler-steam from the steampipe and supply-nozzle 27 through the space around the body ofthe valve between its end pistons,` 19 20, and through the port 23 to the smaller piston-space, 16, such steam acting upon the smaller piston-a rea on the sidc next the trunk, and effecting the left-hand stroke of the piston 8. By its ensuing movement to the leftl the valve next exhausts the steam from the smaller piston-space,16, into thelarger piston-space, 17, on the opposite side ofthe piston, by placing` the cylinder-ports 23 and 24 in communication through the valve-ports 25 and 26 and the interior of the body of the valve, such exhaust-steam acting at correspondingly-reduced pressure on the larger piston-Space, 1T, upon the full area ofthe piston. and effecting the right-hund stroke thereof. The valve next moves to the right, thereby opening the port 23, to receive boiler steam for the succeeding left-hand stroke, and placing the port 24 in communication withthe exhaust opening 28, through which the lowpressure steam which has effected the righthand stroke ot' the piston is exhausted to the atmosphere or to a condenser, as the case may be.

The automatic cut-off mechanism by which thel distribution-valve is actuated may hev of any suit-able and preferred construction which embodies as essential elements a'centrfugal governor or regulator fixed upon the crankshaft of the engine, or upon a counter-shaft rotated thereby, and an eccentric mounted freely upon the shaft of the governor, and coupled to the governor, so as to be varied in position thereby transversely to the axis of the shaft, in accordance with the movement of the governor weights under variations of pressure and load, or both. In the instance shown the eccentric 29, which is fitted freely on the crank-shaft by a slot inclosing the same, is pivoted by a pin, 30, to the supporting disk or carrier 3l of a centrifugal governor fixed upon the crank-shaft 6, and is coupled by a link, 32, to the centrifugally-acting governorweights 33. 'The strap 34 of the eccentric isv secured to one end ot' an eccentric-rod, 35, the opposite end of which is coupled to the valvestem 21. The eccentric 29 beingmoved substantially transversely to the shaft by the inward and outward movements ofthe governorweights. the effect ot' changes in its position induced thereby is to increase or diminish, as required, the length of traverse ofthe distributton-valve without varying the lead thereof, such changes in the traverse of the valve serving to maintain proper regulation by increasing or diminishing the supply of steam, and not changing to any material degree the adj usted grade of expansion at which the valve will normally performits distribution function.

It will be obvious that where circumstances render such arrangement desirable the governor and eccentric may be mounted upon an independent or counter shaft, to which rota- IIO , will ail tion is imparted from the main or crank shaft, and, further, that as the governor and distribution-valve do notin and of themselves form part of my present invention, the construction of said members may be varied materially from that herein shown without departing from the spirit of my invention.

The function of the automatic cut-off mechanism in the combination is simply to effect the actuation of the distribution-valve and maintain uniform regulation of speed within the limits of a comparatively low grade of expansionfsay not exceeding one half-strokcand such mechanism, unless acting in combination with means for utilizingsteam at a higher grade of expansion, would, as before indicated, be insufficient and unsatisfactory for the attainment of the operative economy desired. The means provided for this purpose consist of differential cylinder-spaces adapted to receive, respectively, boiler-steam and exhauststeam, and these. whether controlled by one or more distributionvalves, would in turn be imperfect, unless when, as under my invention, coacting` with a valve-actuating and speed regulating mechanism of simple construction, which is substantially relieved from the duty of performing cnt-olil functions.

I claim herein as my invention- The combination, in a compound engine, of 3o and having its strap coupled to the stem of ,lo

the distribution-val\'e, and a governor fixed upon the crankshaft and coupled to said eccentric, substantially as set forth.

In testimony whereof I have hereunto set my hand.

H. HERMAN VVES'IINGHGUSE.

Vitnesses:

J. SNOWDEN BELL, R. H. WHLTTLESEY. 

